Dehumidifiers have a humidistat that you can set to maintain a specific humidity level in the room. If you set the humidistat too high (low humidity), the unit may run continuously, which is usually unnecessary and actually not very helpful. Most houses need at least some humidity--for example, to keep woodwork from drying out too much and to control static electricity. Also, extreme dryness is often uncomfortable for people.
You need to clean the container that catches the water from the evaporator coils from time to time. How often depends on how much you use it. Check the condition of this container monthly for a while, to learn whether your unit needs frequent cleaning.
Many dehumidifiers are outfitted with a simple, electrostatic filter in the front grill area that filters the air that passes through them. If your unit has a filter, you should replace or clean it once a year. We carry "Electrostatic filter cut-to-fit" material in our Dehumidifier Parts section.
If the temperature becomes fairly cool in the room where you have your dehumidifier--say 60 degrees Fahrenheit or lower--check the dehumidifier coils to be sure they aren't icing up. If they are, that's not good.